TWI427352B - Fixed-focus lens - Google Patents

Description

Fixed focus lens

The present invention relates to a lens, and more particularly to a fixed-focus lens.

At present, the market size of a small light-emitting diode (LED) projector is only one hundred lumens. To increase the brightness of the projector without increasing the power of the LED, it is necessary to use a large aperture lens to improve the light use efficiency. Enhance the brightness of small LED projectors.

When it comes to the design of large apertures (such as f-number < 2) lenses, aberrations have always been a difficult problem for designers to overcome. A method in which the aberration is improved is, for example, the use of an aspherical lens. For example, U.S. Patent No. 5,920,433 discloses a lens of two aspherical lenses. However, the above lens uses a total of 10 lenses, and the total length of the lens is greater than 75 mm (mm), so the overall volume is large.

In addition, U.S. Patent No. 7,397,610 also discloses a lens comprising two aspherical lenses or at least one molded glass lens. However, since the above lens divides the lens into three groups and zooms by moving the second group lens group, the manufacturing cost is increased a lot. In addition, the f-number of the above lens is only 1.74~2.16. Therefore, if cost is not used without using an aspherical lens, and at the same time, it is desired to achieve an effect of improving aberrations, it is necessary to use more lenses. For example, U.S. Patent No. 7,173,766 uses 15 lenses to achieve the effect of improving aberrations. On the other hand, the Republic of China Patent Open No. 201011337 Also disclosed is a first lens group including positive refracting power and a second lens group having positive refracting power, and an aspherical lens is used in both the first lens group and the second lens group, but the f-number of the above lens is 3.24. The aperture is small.

The present invention provides a fixed focus lens that combines lower cost with better optical characteristics.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

In order to achieve one or a part or all of the above or other purposes, an embodiment of the present invention provides a fixed focus lens disposed between an enlarged side and a reduced side, and includes a first lens group and a The second lens group. The first lens group includes a first lens, and the first lens is an aspheric lens. The second lens group has a positive refractive power and is disposed between the first lens group and the reduction side. The second lens group includes a second lens, and the second lens is an aspherical lens, and the f-number of the fixed-focus lens is ≦2. The fixed focus lens is focused by moving the first lens group and the second lens group, and the fixed focus lens satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.5<L/BFL< 3.5, where f is the focal length of the fixed focus lens, f1 is the effective focal length of the first lens group, f2 is the effective focal length of the second lens group, L is the total length of the fixed focus lens, and BFL is the back focus length of the fixed focus lens.

Based on the above, embodiments of the invention include at least one of the following advantages or benefits. Since the fixed focus lens of the embodiment of the present invention includes two aspherical lenses, and the overall structure of the fixed focus lens satisfies the above conditional condition, It has a large aperture and can correct aberrations to achieve good image quality. In addition, the fixed-focus lens of the embodiment of the present invention has a lower cost because it uses fewer lenses and has a simple focusing mode, which simplifies the mechanism design and reduces assembly difficulty.

The above described features and advantages of the present invention will be more apparent from the following description.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the embodiments of the invention. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only directions referring to the additional drawings. Therefore, the directional terminology used is for the purpose of illustration and not limitation.

First embodiment

1 is a schematic structural view of a fixed focus lens according to a first embodiment of the present invention. Referring to FIG. 1 , the fixed focus lens 100 of the embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 110 and a second lens group 120 sequentially arranged from the enlarged side to the reduced side. . The first lens group 110 includes a lens 112, and the lens 112 is an aspheric lens. The second lens group 120 has a positive refracting power and is disposed between the first lens group 110 and the reduction side. The second lens group 120 includes a lens 122, and the lens 122 is an aspheric lens.

In the embodiment, the fixed focus lens 100 is focused by moving the first lens group 110 and the second lens group 120, and the fixed focus lens 100 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.5<L/BFL<3.5, where f is the focal length of the fixed focus lens 100, and f1 is the effective focal length of the first lens group 110. (effective focal length, EFL), f2 is the effective focal length of the second lens group 120, L is the total length of the fixed focus lens 100, and BFL is the back focal length of the fixed focus lens 100.

As shown in FIG. 1 , the diopter of the first lens group 110 of the present embodiment is positive, for example, and the first lens group 110 further includes a lens 114 , wherein the lens 114 is disposed between the lens 112 and the second lens group 120 . However, in other embodiments, the lens 114 can also be disposed between the magnification side and the lens 112. In addition to this, the effective focal length of the lens 112 is fasp1, and the fixed focus lens 100 satisfies the condition of 0.1<|fasp1/f1|<11. The lens 112 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 112 is negative.

In addition, the fixed focus lens 100 further includes an aperture stop 130. The aperture stop 130 is disposed between the first lens group 110 and the second lens group 120. In the present embodiment, the second lens group 120 further includes a lens 124 and a lens 126, and the diopter of the lens 124 and the lens 126 are negative and positive, respectively. The lens 124 and the lens 126 are disposed between the aperture stop 130 and the lens 122.

Specifically, in the embodiment, the lens 114 is a lenticular lens, the lens 124 is a double concave lens, the lens 126 is a lenticular lens, and the lens 122 is a lenticular lens. In addition, in the present embodiment, the lens 112 of the first lens group 110 constituting the fixed focus lens 100 and the lens 122 of the second lens group 120 are aspherical lenses, and the remaining three lenses are spherical lenses. The lens 112 of the first lens group 110 and the lens 122 of the second lens group 120 can effectively improve spherical aberration, 彗 Differences (coma), distortion, and astigmatism, while the combination of negative and positive diopter of the lens in the second lens group 120 can reduce the coma and distortion of the fixed focus lens 100. On the other hand, the use of a low dispersion material to form the lens 126 can effectively reduce the color aberration that the aperture lens does not easily eliminate.

In addition, in the present embodiment, the lens 122 is one of the second lens groups 120 farthest from the aperture stop 130, and the fixed focus lens 100 also satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5.

In general, an image processing device 140 may be disposed on the reduction side. In this embodiment, the image processing component 140 is, for example, a light valve, and the light valve is, for example, a digital micro-mirror device (DMD), a liquid-crystal-on liquid crystal panel. -silicon panel, LCOS panel) or a transmissive liquid crystal panel (transmissive LCD). In addition, the fixed focus lens 100 in this embodiment is adapted to image the image provided by the image processing element 140 on the magnification side. In addition, a glass cover 150 may be disposed in front of the image processing component 140 to protect the image processing component 140.

On the other hand, the fixed focus lens 100 of the embodiment further includes an optical element 160. The optical component 160 is disposed between the second lens group 120 and the image processing component 140. The optical component 160 is, for example, a total internal reflection prism (TIR prism), which can be applied to a projection device.

One embodiment of the fixed focus lens 100 will be described below. It should be noted that the data listed in Table 1 below is not intended to limit the present invention, and any one of ordinary skill in the art can make appropriate changes to its parameters or settings after referring to the present invention. However, it should still fall within the scope of the invention.

In Table 1, the radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. The thickness and refraction of each lens and each optical component in the remark column For the rate and Abbe number, please refer to the values corresponding to the spacing, thickness and Abbe number in the same column.

Further, in Table 1, the surface S1 is the surface of the lens 112 facing the magnification side, and the surface S2 is the surface of the lens 112 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 114, the surfaces S5, S6 are the two surfaces of the lens 124, the surfaces S7, S8 are the two surfaces of the lens 126, and the surfaces S9, S10 are the two surfaces of the lens 122. The surfaces S11, S12 are the two surfaces of the optical element 160.

Furthermore, the above surfaces S1, S2, S9, and S10 are aspherical, and they can be expressed by the following formula:

Where Z is the offset (sag) in the direction of the optical axis, and c is the reciprocal of the radius of the osculating sphere, that is, the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table) The countdown. K is a conic constant, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens to the edge of the lens, and A ₁ ~ A _{7 are} aspheric coefficients, wherein The coefficients A ₁ and A ₇ are 0. Listed in Table 2 are the parameter values of the surfaces S1, S2, S9, and S10.

In the present embodiment, the effective focal length (EFL) of the fixed focus lens 100 is, for example, 14.79 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 55.6 degrees.

2A to 2C are diagrams of imaging optical simulation data of the fixed focus lens 100 of Fig. 1. Please refer to FIG. 2A to FIG. 2C , wherein FIG. 2A is a graph of field curvature and distortion from left to right, FIG. 2B is a spherical aberration, and FIG. 2C is a horizontal direction. The color difference (lateral color). In the field curvature graph, the horizontal axis represents the distance from the focal plane, and the vertical axis represents the size of the field from 0 to the maximum field 1. In the distorted graph, the horizontal axis represents the percentage of distortion, while the vertical axis represents from 0 to the maximum field 1. In the spherical aberration diagram, the horizontal axis is the distance from the paraxial approximate focal plane, and the vertical axis is the field from 0 to 1. In the lateral chromatic aberration diagram of Fig. 2C, the simulation is performed here with green light, wherein the horizontal axis is the distance from the green light and the vertical axis is the field from 0 to 1. The graph shown in FIGS. 2A to 2C shows that the fixed focus lens 100 of the present embodiment has good image quality.

Second embodiment

3 is a schematic structural view of a fixed focus lens according to a second embodiment of the present invention. Referring to FIG. 3, the fixed focus lens 200 of the embodiment is disposed between an enlarged side and a reduced side, and includes a sequence from the enlarged side to the reduced side. A first lens group 210 and a second lens group 220. The first lens group 210 includes a lens 212, and the lens 212 is an aspheric lens. The second lens group 220 has a positive refractive power and is disposed between the first lens group 210 and the reduction side. The second lens group 220 includes a lens 222, and the lens 222 is an aspheric lens. The fixed focus lens 200 is focused by moving the first lens group 210 and the second lens group 220.

In the present embodiment, the lens 222 has a negative refracting power, and the lens 222 is one of the second lens groups 220 that is closest to the aperture stop 130. In addition, the fixed focus lens 200 satisfies 0.2<| f/f1 |<1, 0.3<| f/f2 |<1, and 1.5<L/BFL<3.5, where f is the focal length of the fixed focus lens 200, f1 The effective focal length of the first lens group 210, f2 is the effective focal length of the second lens group 220, L is the total length of the fixed focus lens 200, and the BFL is the back focus length of the fixed focus lens 200. The lens 212 of the first lens group 210 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 212 is negative. In detail, the effective focal length of the lens 212 is fasp1, and 0.5<| fasp1/f1 |<3.

As shown in FIG. 3, the diopter of the first lens group 210 of the present embodiment is, for example, positive, and the first lens group 210 includes two lenses. In detail, the first lens group 210 further includes a lens 214 , wherein the lens 214 is disposed between the lens 212 and the second lens group 220 .

On the other hand, the second lens group 220 further includes a lens 224 and a lens 226 which are sequentially arranged from the magnification side to the reduction side. The lens 224 and the lens 226 are disposed between the lens 222 and the reduction side. In addition, the diopter of the lens 224 and the lens 226 are negative and positive, respectively, and the lens 224 and the lens 226 constitute a double cemented lens. In addition, the second lens group 220 further includes a lens 228. The lens 228 is disposed between the lens 226 and the reduced side, and the diopter of the lens 228 is positive. From this, it can be seen that the diopter of the lens 222, the lens 224, the lens 226, and the lens 228 are negative, negative, positive, and positive, respectively.

Specifically, in the embodiment, the lens 214 is a lenticular lens, the lens 222 is a convex-concave lens with a concave surface facing the magnification side, the lens 224 is a double concave lens, the lens 226 is a lenticular lens, and the lens 228 is a lenticular lens. . In addition, in the present embodiment, the lens 212 and the lens 222 constituting the fixed focus lens 200 are aspherical lenses, and the remaining four lenses are spherical lenses. The lens 212 and the lens 222 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 220 can reduce the coma and distortion of the fixed focus lens 200. On the other hand, the use of low dispersion materials to form the lenses 226, 228 can reduce the chromatic aberration that is difficult to eliminate with large aperture lenses. The double cemented lens formed by the lens 224 and the lens 226 can reduce spherical aberration and chromatic aberration. One of the double cemented lenses is made of a low dispersion material, such as lens 226, which effectively reduces chromatic aberration.

One embodiment of the fixed focus lens 200 will be described below. It should be noted that the data listed in Table 3 below is not intended to limit the present invention, and any one of ordinary skill in the art can make appropriate changes to its parameters or settings after referring to the present invention. However, it should still fall within the scope of the invention.

In Table 3, the radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 3, the surface S1 is the surface of the lens 212 facing the magnification side, and the surface S2 is the surface of the lens 212 facing the reduction side. The surfaces S3 and S4 are the two surfaces of the lens 214, and the surfaces S5 and S6 are the two surfaces of the lens 222. surface. The surface S7 is the surface of the lens 224 facing the magnification side, the surface S8 is the surface of the lens 224 and the lens 226, and the surface S9 is the surface of the lens 226 facing the reduction side. The surfaces S10, S11 are the two surfaces of the lens 228. The surfaces S12, S13 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S5, and S6 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Listed in Table 4 are the parameter values of the surfaces S1, S2, S5, and S6.

In the present embodiment, the effective focal length of the fixed focus lens 200 is, for example, 15.9 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 55.6 degrees.

4A to 4C are diagrams of imaging optical simulation data of the fixed focus lens 200 of FIG. Please refer to FIG. 4A to FIG. 4C , wherein FIG. 4A is a graph of field curvature and distortion from left to right, FIG. 4B is a spherical aberration diagram, and FIG. 4C is a lateral chromatic aberration diagram. Since the patterns shown in FIGS. 4A to 4C are all within the standard range, the fixed focus lens 200 of the present embodiment has good image quality.

Third embodiment

FIG. 5 is a schematic structural view of a fixed focus lens according to a third embodiment of the present invention. Referring to FIG. 5 , the fixed focus lens 300 of the embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 310 and a second lens group 320 sequentially arranged from the enlarged side to the reduced side. . The first lens group 310 includes a lens 312, and the lens 312 is an aspheric lens. The second lens group 320 has a positive refracting power and is disposed between the first lens group 310 and the reduction side. The second lens group 320 includes a lens 322, and the lens 322 is an aspheric lens. The fixed focus lens 300 is focused by moving the first lens group 310 and the second lens group 320.

In the present embodiment, the lens 322 has a negative refracting power, and the lens 322 is one of the second lens groups 320 that is closest to the aperture stop 130. In addition, the fixed focus lens 300 satisfies 0.2<| f/f1 |<1, 0.3<| f/f2 |<1, and 1.5<L/BFL<3.5, where f is the focus of the fixed focus lens 300 The distance f1 is the effective focal length of the first lens group 310, f2 is the effective focal length of the second lens group 320, L is the total length of the fixed focus lens 300, and the BFL is the back focus length of the fixed focus lens 300. The lens 312 of the first lens group 310 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 312 is negative. In detail, the effective focal length of the lens 312 is fasp1, and the fixed focus lens 300 satisfies 0.5<| fasp1/f1 |<3.

As shown in FIG. 5, the diopter of the first lens group 310 of the present embodiment is, for example, positive, and the first lens group 310 includes three lenses. In detail, the first lens group 310 further includes a lens 314 and a lens 316 , wherein the lens 314 and the lens 316 are disposed between the lens 312 and the second lens group 320 .

On the other hand, the second lens group 220 further includes a lens 324 and a lens 326 which are sequentially arranged from the magnification side to the reduction side. The lens 324 and the lens 326 are disposed between the lens 322 and the reduction side. In addition, the diopter of the lens 324 and the lens 326 are negative and positive, respectively, and the lens 324 and the lens 326 constitute a double cemented lens. In addition to this, the second lens group 320 further includes a lens 328. The lens 328 is disposed between the lens 326 and the reduced side, and the diopter of the lens 328 is positive. From this, it can be seen that the diopter of the lens 322, the lens 324, the lens 326, and the lens 328 are negative, negative, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 314 is a convex-concave lens having a concave surface toward the magnification side, and the lens 316 is a lenticular lens. The lens 322 is a convex-concave lens having a concave surface toward the magnification side, the lens 324 is a double concave lens, the lens 326 is a lenticular lens, and the lens 328 is a lenticular lens. In addition, in the present embodiment, the lens 312 and the lens 322 constituting the fixed focus lens 300 are aspherical lenses, and the remaining five lenses are spherical lenses. its The middle lens 312 and the lens 322 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 320 can reduce the coma and distortion of the fixed focus lens 300. On the other hand, the use of a low dispersion material to form the lens 328 can effectively reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double cemented lens formed by the lens 324 and the lens 326 can reduce spherical aberration and chromatic aberration.

One embodiment of the fixed focus lens 300 will be described below. It should be noted that the data listed in Table 5 below is not intended to limit the present invention, and any one of ordinary skill in the art can make appropriate changes to its parameters or settings after referring to the present invention. However, it should still fall within the scope of the invention.

In Table 5, the radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 5, the surface S1 is the surface of the lens 312 facing the magnification side, and the surface S2 is the surface of the lens 312 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 314, the surfaces S5, S6 are the two surfaces of the lens 316, and the surfaces S7, S8 are the two surfaces of the lens 322. The surface S9 is the surface facing the magnification side of the lens 324, the surface S10 is the connection surface of the lens 324 and the lens 326, and the surface S11 is facing the surface on the reduction side. The surfaces S12, S13 are the two surfaces of the lens 328. The surfaces S14, S15 are the two surfaces of the optical element 160.

Furthermore, the above surfaces S1, S2, S7, and S8 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Listed in Table 2 are the parameter values of the surfaces S1, S2, S7, and S8.

In the present embodiment, the effective focal length of the fixed focus lens 300 is, for example, 14.94 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 55.6 degrees.

6A to 6C are imaging optical simulations of the fixed focus lens 300 of FIG. data graph. Referring to FIG. 6A to FIG. 6C, in FIG. 6A, the left-to-right sequence is a field curvature and distortion pattern, FIG. 6B is a spherical aberration diagram, and FIG. 6C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 6A to 6C, the fixed focus lens 300 of the present embodiment has good image quality.

Fourth embodiment

Fig. 7 is a schematic structural view of a fixed focus lens according to a fourth embodiment of the present invention. Referring to FIG. 7 , the fixed focus lens 400 of the embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 410 and a second lens group 420 sequentially arranged from the enlarged side to the reduced side. . The first lens group 410 includes a lens 412, and the lens 412 is an aspheric lens. The second lens group 420 has a positive refractive power and is disposed between the first lens group 410 and the reduction side. The second lens group 420 includes a lens 422, and the lens 422 is an aspheric lens. The fixed focus lens 400 is focused by moving the first lens group 410 and the second lens group 420.

In the present embodiment, lens 422 has a positive power and lens 422 is one of the second lens group 420 that is furthest from aperture stop 130. In addition, the fixed focus lens 400 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 400, f1 The effective focal length of the first lens group 410, f2 is the effective focal length of the second lens group 420, L is the total length of the fixed focus lens 400, and the BFL is the back focus length of the fixed focus lens 400. Further, the lens 412 of the first lens group 410 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 412 is negative. In detail, the effective focal length of the lens 412 is fasp1, and the fixed focus lens 400 Meet 0.1<| fasp1/f1 |<11.

As shown in FIG. 7, the diopter of the first lens group 410 of the present embodiment is, for example, positive, and the first lens group 310 includes three lenses. In detail, the first lens group 410 further includes a lens 414 and a lens 416 , wherein the lens 414 and the lens 416 are disposed between the lens 412 and the second lens group 420 . However, in other embodiments, the lens 412 can also be disposed between the lens 414 and the lens 416. That is, the lens 412 may be the first sheet or the second sheet from the enlarged side in the first lens group 410.

On the other hand, the second lens group 420 further includes a lens 424 and a lens 426 which are sequentially arranged from the magnification side to the reduction side. The lens 424 and the lens 426 are disposed between the aperture stop 130 and the lens 422. In addition, the diopter of the lens 424 and the lens 426 are negative and positive, respectively, and the lens 424 and the lens 426 constitute a double cemented lens. In addition to this, the second lens group 420 further includes a lens 428. Lens 428 is disposed between lens 426 and lens 422, and the diopter of lens 428 is positive. From this, it is understood that the diopter of the lens 424, the lens 426, the lens 428, and the lens 422 are negative, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 414 is a convex-concave lens having a concave surface toward the magnification side, and the lens 416 is a lenticular lens. Lens 424 is a double concave lens, lens 426 is a lenticular lens, and lens 428 is a lenticular lens. In addition, in the present embodiment, the lens 412 and the lens 422 constituting the fixed focus lens 400 are aspherical lenses, and the remaining five lenses are spherical lenses. The lens 412 and the lens 422 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 420 can reduce the coma and distortion of the fixed focus lens 400. On the other hand, by making Making the lenses 414, 426 with a low dispersion material can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double-glued lens formed by the lens 424 and the lens 426 can reduce spherical aberration and chromatic aberration, and one lens, such as the lens 426, is made of a low-dispersion material, which can effectively reduce chromatic aberration.

One embodiment of the fixed focus lens 400 will be described below. It should be noted that the data listed in Table VII below is not intended to limit the present invention, and any one of ordinary skill in the art can make appropriate changes to its parameters or settings after referring to the present invention. However, it should still fall within the scope of the invention.

In Table 7, the radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 7, the surface S1 is the surface of the lens 412 facing the magnification side, and the surface S2 is the surface of the lens 412 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 414, and the surfaces S5, S6 are the two surfaces of the lens 416. The surface S7 is the surface facing the magnification side of the lens 424, the surface S8 is the connection surface of the lens 424 and the lens 426, and the surface S9 is the surface of the lens 426 facing the reduction side. The surfaces S10, S11 are the two surfaces of the lens 428, the surfaces S12, S13 are the two surfaces of the lens 422, and the surfaces S14, S15 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S12, and S13 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Table 8 lists the parameter values of the surfaces S1, S2, S12, and S13.

In the present embodiment, the effective focal length of the fixed focus lens 400 is, for example, 14.74 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 55.6 degrees.

8A to 8C are diagrams of imaging optical simulation data of the fixed focus lens 400 of Fig. 7. Referring to FIG. 8A to FIG. 8C, in FIG. 8A, the left-to-right sequence is a field curvature and distortion pattern, FIG. 8B is a spherical aberration diagram, and FIG. 8C is a lateral chromatic aberration diagram. The graphs shown in Figs. 8A to 8C all show that the fixed focus lens 400 of the present embodiment has good image quality.

Fifth embodiment

FIG. 9 is a schematic structural view of a fixed focus lens according to a fifth embodiment of the present invention. Referring to FIG. 9 , the fixed focus lens 500 of the embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 510 and a second lens group 520 sequentially arranged from the enlarged side to the reduced side. . The first lens group 510 includes a lens 512, and the lens 512 is an aspheric lens. The second lens group 520 has a positive refractive power and is disposed between the first lens group 510 and the reduction side. The second lens group 520 includes a lens 522, and the lens 522 is an aspheric lens. The fixed focus lens 500 is focused by moving the first lens group 510 and the second lens group 520.

In the present embodiment, lens 522 has a positive power and lens 522 is one of the second lens group 520 that is furthest from aperture stop 130. In addition, the fixed focus lens 500 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 500, f1 The effective focal length of the first lens group 510, f2 is the effective focal length of the second lens group 520, L is the total length of the fixed focus lens 500, and the BFL is the back focus length of the fixed focus lens 500. Further, the lens 512 of the first lens group 510 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 512 is negative. In detail, the effective focal length of the lens 512 is fasp1, and the fixed focus lens 500 satisfies 0.1<| fasp1/f1 |<11.

As shown in FIG. 9, the diopter of the first lens group 510 of the present embodiment is, for example, positive, and the first lens group 510 includes four lenses. In detail, the first lens group 510 further includes a lens sequentially arranged from the enlarged side to the reduced side. 514, lens 516 and lens 518, wherein lens 514, lens 516 and lens 518 are disposed between lens 512 and second lens group 520. However, in other embodiments, lens 512 can also be disposed between lens 514 and lens 516. That is, the lens 512 may be the first sheet or the second sheet from the enlarged side in the first lens group 510.

On the other hand, the second lens group 520 further includes a lens 524 and a lens 526 which are sequentially arranged from the magnification side to the reduction side. The lens 524 and the lens 526 are disposed between the aperture stop 130 and the lens 522. In addition, the diopter of the lens 524 and the lens 526 are negative and positive, respectively, and the lens 524 and the lens 526 constitute a double cemented lens. In addition to this, the second lens group 520 further includes a lens 528. Lens 528 is disposed between lens 526 and lens 522, and the diopter of lens 528 is positive. From this, it can be seen that the diopter of the lens 524, the lens 526, the lens 528, and the lens 522 are negative, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 514 is a convex-concave lens having a concave surface facing the magnification side, the lens 516 is a meniscus lens having a concave surface facing the magnification side, and the lens 518 is a meniscus lens having a convex surface facing the magnification side. Lens 524 is a double concave lens, lens 526 is a lenticular lens, and lens 528 is a lenticular lens. In addition, in the present embodiment, the lens 512 and the lens 522 constituting the fixed focus lens 500 are aspherical lenses, and the remaining six lenses are spherical lenses. The lens 512 and the lens 522 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 520 can reduce the coma and distortion of the fixed focus lens 500. On the other hand, making the lens 526 by using a low dispersion material can reduce the color of the large aperture lens. difference. The double cemented lens formed by the lens 524 and the lens 526 can reduce spherical aberration and chromatic aberration, and one lens, such as the lens 526, can be effectively reduced in chromatic aberration by using a low dispersion material.

One embodiment of the fixed focus lens 500 will be described below. It should be noted that the data listed in Table IX below is not intended to limit the present invention, and any one of ordinary skill in the art can make appropriate changes to its parameters or settings after referring to the present invention. However, it should still fall within the scope of the invention.

In Table 9, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 9, the surface S1 is the surface of the lens 512 facing the magnification side, and the surface S2 is the surface of the lens 512 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 514, the surfaces S5, S6 are the two surfaces of the lens 516, and the surfaces S7, S8 are the two surfaces of the lens 518. The surface S9 is the surface facing the magnification side of the lens 524, the surface S10 is the connection surface of the lens 524 and the lens 526, and the surface S11 is facing the surface on the reduction side. The surfaces S12, S13 are the two surfaces of the lens 528, and the surfaces S14, S15 are the two surfaces of the lens 522. The surfaces S16, S17 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S14, and S15 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the lens center to the lens edge, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ , A ₆ , A ₇ is 0. Listed in Table 10 are the parameter values of the surfaces S1, S2, S14, and S15.

In the present embodiment, the effective focal length of the fixed focus lens 500 is, for example, 14.69 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 55.6 degrees.

10A to 10C are diagrams of imaging optical simulation data of the fixed focus lens 500 of Fig. 9. Please refer to FIG. 10A to FIG. 10C , in which FIG. 10A is a graph of field curvature and distortion from left to right, FIG. 10B is a spherical aberration diagram, and FIG. 10C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 10A to 10C, the fixed focus lens 500 of the present embodiment has good image quality.

Sixth embodiment

Figure 11 is a schematic view showing the structure of a fixed focus lens according to a sixth embodiment of the present invention. Referring to FIG. 11 , the fixed focus lens 600 of the present embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 610 and a second lens group 620 sequentially arranged from the enlarged side to the reduced side. . The first lens group 610 includes a lens 612, and the lens 612 is an aspheric lens. The second lens group 620 has a positive refracting power and is disposed between the first lens group 610 and the reduction side. The second lens group 620 includes a lens 622, and the lens 622 is an aspheric lens. The fixed focus lens 600 focuses by moving the first lens group 610 and the second lens group 620.

In the present embodiment, lens 622 has a positive power and lens 622 is one of the second lens group 620 that is furthest from aperture stop 130. In addition, the fixed focus lens 600 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 600, f1 The effective focal length of the first lens group 610, f2 is the effective focal length of the second lens group 620, L is the total length of the fixed focus lens 600, and the BFL is the back focus length of the fixed focus lens 600. Further, the lens 612 of the first lens group 610 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 612 is negative. In detail, the effective focal length of the lens 612 is fasp1, and 0.1<| fasp1/f1 |<11.

As shown in FIG. 11, the diopter of the first lens group 610 of the present embodiment is, for example, negative, and the first lens group 610 includes two lenses. In detail, the first lens group 610 further includes a lens 614, wherein the lens 612 is configured to be transparent Between the mirror 614 and the second lens group 620. However, in other embodiments, the lens 614 can also be disposed between the lens 612 and the second lens group 620. That is, the aspherical lens (lens 612) may be the second or first lens from the magnification side in the first lens group 610.

On the other hand, the second lens group 620 further includes a lens 624 and a lens 626 which are sequentially arranged from the magnification side to the reduction side. The lens 624 and the lens 626 are disposed between the aperture stop 130 and the lens 622. In addition, the diopter of the lens 624 and the lens 626 are negative and positive, respectively, and the lens 624 and the lens 626 constitute a double cemented lens. In addition, the second lens group 620 further includes a lens 628 and a lens 629. Lens 628 and lens 629 are disposed between lens 626 and lens 622, and the diopter of lens 628 and lens 629 is positive. From this, it is understood that the diopter of the lens 624, the lens 626, the lens 628, the lens 629, and the lens 622 are negative, positive, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 614 is a meniscus lens having a convex surface facing the magnification side. Lens 624 is a double concave lens, lens 626 is a lenticular lens, lens 628 is a lenticular lens, and lens 629 is a lenticular lens. In addition, in the present embodiment, the lens 612 and the lens 622 constituting the fixed focus lens 600 are aspherical lenses, and the remaining five lenses are spherical lenses. The lens 612 and the lens 622 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 620 can reduce the coma and distortion of the fixed focus lens 600. On the other hand, the use of a low dispersion material to form the lens 628 or 629 can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double-glued lens formed by the lens 624 and the lens 626 can lower the ball Aberration and chromatic aberration.

One embodiment of the fixed focus lens 600 will be described below. It should be noted that the data listed in Table 11 below is not intended to limit the present invention, and any person having ordinary knowledge in the art can appropriately change its parameters or settings after referring to the present invention. However, it should still fall within the scope of the present invention.

In Table 11, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 11, the surface S1 is the surface of the lens 614 facing the magnification side, and the surface S2 is the surface of the lens 614 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 612. The surface S5 is the surface of the lens 624 facing the magnification side, the surface S6 is the surface of the lens 624 and the lens 626, and the surface S7 is facing the surface of the reduction side. The surfaces S8, S9 are the two surfaces of the lens 628, the surfaces S10, S11 are the two surfaces of the lens 629, and the surfaces S12, S13 are the two surfaces of the lens 622. The surfaces S14, S15 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S3, S4, S12, and S13 are aspherical surfaces, and they can be expressed by the following formula:

Where Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is a quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, wherein the coefficient A ₁ is zero. Listed in Table 12 are the parameter values of the surfaces S3, S4, S12, and S13.

In the present embodiment, the effective focal length of the fixed focus lens 600 is, for example, 17.95 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 46.2 degrees.

12A to 12C are diagrams of imaging optical simulation data of the fixed focus lens 600 of Fig. 11. Referring to FIG. 12A to FIG. 12C, in FIG. 12A, the left-to-right sequence is a field curvature and distortion pattern, FIG. 12B is a spherical aberration diagram, and FIG. 12C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 12A to 12C, the fixed focus lens 600 of the present embodiment has good image quality.

Seventh embodiment

Figure 13 is a schematic view showing the structure of a fixed focus lens according to a seventh embodiment of the present invention. Referring to FIG. 13 , the fixed focus lens 700 of the present embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 710 and a second lens group 720 sequentially arranged from the enlarged side to the reduced side. . The first lens group 710 includes a lens 712, and the lens 712 is an aspheric lens. The second lens group 720 has a positive refracting power and is disposed between the first lens group 710 and the reduction side. The second lens group 720 includes a lens 722, and the lens 722 is an aspheric lens. The fixed focus lens 700 is focused by moving the first lens group 710 and the second lens group 720.

In the present embodiment, lens 722 has a positive power and lens 722 is one of the second lens groups 720 that is furthest from aperture stop 130. In addition, the fixed focus lens 700 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 700, f1 The effective focal length of the first lens group 710, f2 is the effective focal length of the second lens group 720, L is the total length of the fixed focus lens 700, and the BFL is the back focus length of the fixed focus lens 700. Further, the lens 712 of the first lens group 710 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 712 is negative. In detail, the effective focal length of the lens 712 is fasp1, and 0.1<| fasp1/f1 |<11.

As shown in FIG. 13, the diopter of the first lens group 710 of the present embodiment is, for example, positive, and the first lens group 710 includes four lenses. In detail, the first lens group 710 further includes a lens 714, a lens 716 and a lens 718 which are sequentially arranged by the reduction side of the magnification side, wherein the lens 714 and the lens 716 are transparent. The mirror 718 is disposed between the lens 712 and the second lens group 720.

On the other hand, the second lens group 720 further includes a lens 724 and a lens 726 which are sequentially arranged from the magnification side to the reduction side. The lens 724 and the lens 726 are disposed between the first lens group 710 and the lens 722. In addition, the diopter of the lens 724 and the lens 726 are negative and positive, respectively, and the lens 724 and the lens 726 constitute a double cemented lens. In addition to this, the second lens group 720 further includes a lens 728. Lens 728 is disposed between lens 726 and lens 722, and the diopter of lens 728 is positive. From this, it can be seen that the diopter of the lens 724, the lens 726, the lens 728, and the lens 722 are negative, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 714 is a double concave lens, the lens 716 is a concave-convex lens whose concave surface faces the magnification side, and the lens 718 is a plano-convex lens whose convex surface faces the magnification side. Lens 724 is a double concave lens, lens 726 is a lenticular lens, and lens 728 is a lenticular lens. In addition, in the present embodiment, the lens 712 and the lens 722 constituting the fixed focus lens 700 are aspherical lenses, and the remaining six lenses are spherical lenses. The lens 712 and the lens 722 can effectively improve the spherical aberration, coma, distortion and astigmatism, and the combination of the negative and positive diopter in the second lens group 720 can reduce the coma and distortion of the fixed focus lens 700. On the other hand, the use of a low dispersion material to form the lens 726 can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double cemented lens formed by the lens 724 and the lens 726 can reduce spherical aberration and chromatic aberration, and one lens, such as the lens 726, can be effectively reduced in chromatic aberration by using a low dispersion material.

One embodiment of the fixed focus lens 700 will be described below. It should be noted that the data listed in Table 13 below is not intended to limit the issue. It will be apparent to those skilled in the art that the present invention may be modified as appropriate, even if it is within the scope of the invention.

In Table 13, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 13, the surface S1 is the surface of the lens 712 facing the magnification side, and the surface S2 is the surface of the lens 712 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 714, the surfaces S5, S6 are the two surfaces of the lens 716, and the surfaces S7, S8 are the two surfaces of the lens 718. The surface S9 is the surface of the lens 724 facing the magnification side, the surface S10 is the surface of the lens 724 and the lens 726, and the surface S11 is facing the surface of the reduction side. The surfaces S12, S13 are the two surfaces of the lens 728, and the surfaces S14, S15 are the two surfaces of the lens 722. The surfaces S16, S17 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S14, and S15 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Listed in Table XIV are the parameter values of the surfaces S1, S2, S14, and S15.

In the present embodiment, the effective focal length of the fixed focus lens 700 is, for example, 14.02 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 60 degrees.

14A to 14C are diagrams of imaging optical simulation data of the fixed focus lens 700 of Fig. 13. Referring to FIG. 14A to FIG. 14C, in FIG. 14A, the pattern of field curvature and distortion is sequentially from left to right, FIG. 14B is a spherical aberration diagram, and FIG. 14C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 14A to 14C, the fixed focus lens 700 of the present embodiment has good image quality.

Eighth embodiment

Figure 15 is a schematic view showing the structure of a fixed focus lens according to an eighth embodiment of the present invention; Figure. Referring to FIG. 15 , the fixed focus lens 800 of the embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 810 and a second lens group 820 sequentially arranged from the enlarged side to the reduced side. . The first lens group 810 includes a lens 812 and the lens 812 is an aspheric lens. The second lens group 820 has a positive refracting power and is disposed between the first lens group 810 and the reduction side. The second lens group 820 includes a lens 822, and the lens 822 is an aspheric lens. The fixed focus lens 800 is focused by moving the first lens group 810 and the second lens group 820.

In the present embodiment, lens 822 has a positive power and lens 822 is one of the second lens group 820 that is furthest from aperture stop 130. In addition, the fixed focus lens 800 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 800, f1 The effective focal length of the first lens group 810, f2 is the effective focal length of the second lens group 820, L is the total length of the fixed focus lens 800, and the BFL is the back focus length of the fixed focus lens 800. Further, the lens 812 of the first lens group 810 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 812 is negative. In detail, the effective focal length of the lens 812 is fasp1, and the fixed focus lens 800 satisfies 0.1<| fasp1/f1 |<11.

As shown in FIG. 15, the diopter of the first lens group 810 of the present embodiment is, for example, positive, and the first lens group 810 includes three lenses. In detail, the first lens group 810 further includes a lens 814 and a lens 816 which are sequentially arranged by the reduction side of the magnification side, wherein the lens 814 and the lens 816 are disposed between the lens 812 and the second lens group 820.

On the other hand, the second lens group 820 further includes an enlarged side to a reduced side The lens 824 and the lens 826 are sequentially arranged. The lens 824 and the lens 826 are disposed between the aperture stop 130 and the lens 822. In addition, the diopter of the lens 824 and the lens 826 are negative and positive, respectively, and the lens 824 and the lens 826 constitute a double cemented lens. In addition to this, the second lens group 820 further includes a lens 828 and a lens 829. Lens 828 and lens 829 are disposed between lens 826 and lens 822, and the diopter of lens 828 and lens 829 is positive. From this, it can be seen that the diopter of the lens 824, the lens 826, the lens 828, the lens 829, and the lens 822 are negative, positive, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 814 is a convex-concave lens with a convex surface facing the magnification side, and the lens 816 is a lenticular lens. The lens 824 is a double concave lens, and the lens 826, the lens 828, and the lens 829 are both lenticular lenses. In addition, in the present embodiment, the lens 812 and the lens 822 constituting the fixed focus lens 800 are aspherical lenses, and the remaining six lenses are spherical lenses. The lens 812 and the lens 822 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 820 can reduce the coma and distortion of the fixed focus lens 800. On the other hand, the use of a low dispersion material to form the lens 814, 826 or 829 can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double cemented lens formed by the lens 824 and the lens 826 can reduce spherical aberration and chromatic aberration, and one lens such as the lens 826 can be effectively reduced in chromatic aberration by using a low dispersion material.

One embodiment of the fixed focus lens 800 will be described below. It should be noted that the data sheets listed in Table 15 below are not intended to limit the present invention, and those having ordinary knowledge in the art can appropriately change their parameters or settings after referring to the present invention. But it should still belong to this Within the scope of the invention.

In Table 15, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 15, the surface S1 is the surface of the lens 812 facing the magnification side, and the surface S2 is the surface of the lens 812 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 814, the surfaces S5, S6 are the two surfaces of the lens 816, the surface S7 is the surface facing the magnification side of the lens 824, the surface S8 is the connecting surface of the lens 824 and the lens 826, and the surface S9 is the lens. 826 faces the surface of the reduced side. The surfaces S10, S11 are the two surfaces of the lens 828, the surfaces S12, S13 are the two surfaces of the lens 829, and the surfaces S14, S15 are the two surfaces of the lens 822. The surfaces S16, S17 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S14, and S15 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is a quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, wherein the coefficient A ₁ is zero. Listed in Table 16 are the parameter values of the surfaces S1, S2, S14, and S15.

In the present embodiment, the effective focal length of the fixed focus lens 800 is, for example, 13.76 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 60 degrees.

16A to 16C are diagrams of imaging optical simulation data of the fixed focus lens 800 of Fig. 15. Referring to FIG. 16A to FIG. 16C, in FIG. 16A, a picture of curvature of field and distortion is sequentially from left to right, FIG. 16B is a spherical aberration diagram, and FIG. 16C is a lateral chromatic aberration diagram. The graph shown in Figs. 16A to 16C shows that the fixed focus lens 800 of the present embodiment has good image quality.

Ninth embodiment

Figure 17 is a schematic view showing the structure of a fixed focus lens according to a ninth embodiment of the present invention; Figure. Referring to FIG. 17, the fixed focus lens 900 of the present embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 910 and a second lens group 920 sequentially arranged from the enlarged side to the reduced side. . The first lens group 910 includes a lens 912, and the lens 912 is an aspheric lens. The second lens group 920 has a positive refracting power and is disposed between the first lens group 910 and the reduction side. The second lens group 920 includes a lens 922, and the lens 922 is an aspheric lens. The fixed focus lens 900 focuses by moving the first lens group 910 and the second lens group 920.

In the present embodiment, lens 922 has a positive power and lens 922 is one of the second lens group 920 that is furthest from aperture stop 130. In addition, the fixed focus lens 900 satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 900, f1 The effective focal length of the first lens group 910, f2 is the effective focal length of the second lens group 920, L is the total length of the fixed focus lens 900, and the BFL is the back focus length of the fixed focus lens 900. Further, the lens 912 of the first lens group 910 is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 912 is negative. In detail, the effective focal length of the lens 912 is fasp1, and the fixed focus lens 900 satisfies 0.1<| fasp1/f1 |<11.

As shown in FIG. 17, the diopter of the first lens group 910 of the present embodiment is, for example, positive, and the first lens group 910 includes four lenses. In detail, the first lens group 910 further includes a lens 914, a lens 916 and a lens 918 which are sequentially arranged on the reduction side of the magnification side, wherein the lens 914, the lens 916 and the lens 918 are disposed in the lens 912 and the second lens group 920. between.

On the other hand, the second lens group 920 further includes an enlarged side to a reduced side The lens 924 and the lens 926 are sequentially arranged. Lens 924 and lens 926 are disposed between aperture stop 130 and lens 922. Additionally, the diopter of lens 924 and lens 926 are negative and positive, respectively, and lens 924 and lens 926 form a double cemented lens. In addition to this, the second lens group 920 further includes a lens 928 and a lens 929. Lens 928 and lens 929 are disposed between lens 926 and lens 922, and the diopter of lens 928 and lens 929 is positive. It can be seen that the second lens group 920 of the present embodiment includes five lenses, and the diopter of the lens 924, the lens 926, the lens 928, the lens 929, and the lens 922 are negative, positive, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 914 is a double concave lens, the lens 916 is a lenticular lens, and the lens 918 is a meniscus lens having a convex surface facing the magnification side. The lens 924 is a double concave lens, and the lens 926, the lens 928, and the lens 929 are both lenticular lenses. In this embodiment, the lens 912 and the lens 922 constituting the fixed focus lens 900 are aspherical lenses, and the remaining seven lenses are spherical lenses. The lens 912 and the lens 922 can effectively improve spherical aberration, coma, distortion and astigmatism, and the combination of negative and positive diopter in the second lens group 920 can reduce the coma and distortion of the fixed focus lens 900. On the other hand, the use of a low dispersion material to fabricate the lens 926 or 929 can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. The double cemented lens formed by lens 924 and lens 926 can reduce spherical aberration and chromatic aberration, and one lens, such as lens 926, can be effectively reduced in chromatic aberration by using a low dispersion material.

One embodiment of the fixed focus lens 900 will be described below. It should be noted that the data sheets listed in Table 17 below are not intended to limit the present invention, and any one of ordinary skill in the art is referred to the present invention. Thereafter, appropriate changes may be made to its parameters or settings, but it should still fall within the scope of the present invention.

In Table 17, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 17, the surface S1 is the surface of the lens 912 facing the magnification side, and the surface S2 is the surface of the lens 912 facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 914, the surfaces S5, S6 are the two surfaces of the lens 916, and the surfaces S7, S8 are the two surfaces of the lens 918. The surface S9 is the surface of the lens 924 facing the magnification side, the surface S10 is the surface of the lens 924 and the lens 926, and the surface S11 is facing the surface of the reduction side. The surfaces S12, S13 are the two surfaces of the lens 928, the surfaces S14, S15 are the two surfaces of the lens 929, and the surfaces S16, S17 are the two surfaces of the lens 922. The surfaces S18, S19 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S1, S2, S16, and S17 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is a quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, wherein the coefficient A ₁ is zero. Listed in Table 18 are the parameter values of the surfaces S1, S2, S16, and S17.

In the present embodiment, the effective focal length of the fixed focus lens 900 is, for example, 13.94 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 60 degrees.

18A to 18C are diagrams of imaging optical simulation data of the fixed focus lens 800 of Fig. 17. Referring to FIG. 18A to FIG. 18C, in FIG. 18A, the pattern of curvature of field and distortion is sequentially from left to right, FIG. 18B is a spherical aberration diagram, and FIG. 18C is a lateral chromatic aberration diagram. Figure shown by Figures 18A to 18C As shown, the fixed focus lens 900 of the present embodiment has good image quality.

Tenth embodiment

Figure 19 is a schematic view showing the structure of a fixed focus lens according to a tenth embodiment of the present invention. Referring to FIG. 19, the fixed focus lens 900a of the present embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 910a and a second lens group 920a arranged in order from the enlarged side to the reduced side. . The first lens group 910a includes a lens 912a, and the lens 912a is an aspheric lens. The second lens group 920a has a positive refractive power and is disposed between the first lens group 910a and the reduction side. The second lens group 920a includes a lens 928a, and the lens 928a is an aspheric lens. The fixed focus lens 900a is focused by moving the first lens group 910a and the second lens group 920a.

In the present embodiment, the lens 928a has a negative refracting power, and the lens 928a is one of the second lens group 920a closest to the aperture stop 130. In addition, the fixed focus lens 900a satisfies 0.2<| f/f1 |<1, 0.3<| f/f2 |<1, and 1.5<L/BFL<3.5, where f is the focal length of the fixed focus lens 900a, f1 The effective focal length of the first lens group 910a, f2 is the effective focal length of the second lens group 920a, L is the total length of the fixed focus lens 900a, and the BFL is the back focus length of the fixed focus lens 900a. Further, the lens 912a of the first lens group 910a is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 912a is negative. In detail, the effective focal length of the lens 912a is fasp1, and the fixed focus lens 900a satisfies 0.5<| fasp1/f1 |<3.

As shown in FIG. 19, the diopter of the first lens group 910a of the present embodiment is, for example, positive, and the first lens group 910a includes four lenses. In details, The first lens group 910a further includes a lens 914a, a lens 916a, and a lens 918a, wherein the lens 914a, the lens 916a, and the lens 918a are disposed between the lens 912a and the second lens group 920a.

On the other hand, the second lens group 920a further includes a lens 924a, a lens 926a, and a lens 922a which are sequentially arranged from the magnification side to the reduction side. The lens 924a, the lens 926a, and the lens 922a are disposed between the lens 928a and the reduction side and the diopter of the lens 922a is positive. In addition, the diopter of the lens 924a and the lens 926a are negative and positive, respectively, and the lens 924a and the lens 926a constitute a double cemented lens, and the double cemented lens is the second piece located behind the aperture stop 130. It can be seen that the second lens group 920a of the present embodiment includes four lenses, and the diopter of the lens 928a, the lens 924a, the lens 926a, and the lens 922a are negative, negative, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 914a is a double concave lens, the lens 916a is a lenticular lens, and the lens 918a is a lenticular lens. Lens 924a is a double concave lens, lens 926a is a lenticular lens, and lens 928a is a lenticular lens. In addition, in the present embodiment, the lens 912a and the lens 928a constituting the fixed focus lens 900a are aspherical lenses, and the remaining six lenses are spherical lenses. The lens 912a and the lens 928a can effectively improve distortion and astigmatism, and the combination of positive and negative diopter of other spherical lenses can reduce spherical aberration, coma and curvature of field. The overall negative and positive refracting combination in the second lens group 920a can reduce the coma and distortion of the fixed focus lens 900a. On the other hand, the use of a low dispersion material to form the lens 926a can reduce the chromatic aberration that is difficult to eliminate with a large aperture lens. Double-glued lens formed by lens 924a and lens 926a The spherical aberration and chromatic aberration can be reduced, and one lens, such as lens 926a, is made of a low dispersion material to effectively reduce chromatic aberration.

An embodiment of the fixed focus lens 900a will be described below. It should be noted that the data sheets listed in Table 19 below are not intended to limit the present invention, and those having ordinary knowledge in the art can appropriately change their parameters or settings after referring to the present invention. However, it should still fall within the scope of the present invention.

In Table 19, the radius of curvature refers to the radius of curvature of each surface, and the pitch refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 19, the surface S1 is the surface of the lens 912a facing the magnification side, and the surface S2 is the surface of the lens 912a facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 914a, the surfaces S5, S6 are the two surfaces of the lens 916a, and the surfaces S7, S8 are the two surfaces of the lens 918a. The surfaces S9, S10 are the two surfaces of the lens 928a. The surface S11 is the surface facing the magnification side of the lens 924a, the surface S12 is the connection surface of the lens 924a and the lens 926a, and the surface S13 is facing the surface on the reduction side. The surfaces S14, S15 are the two surfaces of the lens 922a. The surfaces S16, S17 are the two surfaces of the optical element 160.

Furthermore, the above surfaces S1, S2, S9, and S10 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Listed in Table 20 are the parameter values of the surfaces S1, S2, S9, and S10.

In the present embodiment, the effective focal length of the fixed focus lens 900a is, for example, 13.69 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 60 degrees.

20A to 20C are diagrams of imaging optical simulation data of the fixed focus lens 900a of Fig. 19. Please refer to FIG. 20A to FIG. 20C , in which FIG. 20A is a graph of field curvature and distortion from left to right, and FIG. 20B is a spherical aberration diagram. Fig. 20C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 20A to 20C, the fixed focus lens 900a of the present embodiment has good image quality.

Eleventh embodiment

Figure 21 is a schematic view showing the structure of a fixed focus lens according to an eleventh embodiment of the present invention. Referring to FIG. 21, the fixed focus lens 900b of the present embodiment is disposed between an enlarged side and a reduced side, and includes a first lens group 910b and a second lens group 920b sequentially arranged from the enlarged side to the reduced side. . The first lens group 910b includes a lens 912b, and the lens 912b is an aspheric lens. The second lens group 920b has a positive refracting power and is disposed between the first lens group 910b and the reduction side. The second lens group 920b includes a lens 922b, and the lens 922b is an aspheric lens. The fixed focus lens 900b is focused by moving the first lens group 910b and the second lens group 920b.

In the present embodiment, the lens 922b has a positive refracting power, and the lens 922b is one of the second lens group 920b farthest from the aperture stop 130. In addition, the fixed focus lens 900b satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed focus lens 900b, f1 The effective focal length of the first lens group 910b, f2 is the effective focal length of the second lens group 920b, L is the total length of the fixed focus lens 900b, and the BFL is the back focus length of the fixed focus lens 900b. Further, the lens 912b of the first lens group 910b is a meniscus lens whose convex surface faces the magnification side, and the diopter of the lens 912b is negative. In detail, the effective focal length of the lens 912b is fasp1, and 0.1<| fasp1/f1 |<11.

As shown in FIG. 21, the diopter of the first lens group 910b of this embodiment For example, positive, and the first lens group 910b includes five lenses. In detail, the first lens group 910b further includes a lens 914b, wherein the lens 914b is located between the magnification side and the lens 912b. That is, the lens 912b is a second sheet lens from the magnification side in the first lens group 910b. In addition, the first lens group 910b further includes a lens 916b, a lens 918b, and a lens 919b, wherein the lens 916b, the lens 918b, and the lens 919b are disposed between the lens 912b and the second lens group 920b. Lens 916b and lens 918b form a double cemented lens and are located between lens 912b and aperture stop 130. In detail, in the present embodiment, the double cemented lens constituted by the lens 916b and the lens 918b is located in the next piece of the aspherical lens (lens 912b).

On the other hand, the second lens group 920b further includes a lens 924b and a lens 926b which are sequentially arranged from the magnification side to the reduction side. The lens 924b and the lens 926b are disposed between the first lens group 910b and the lens 922b. In addition, the diopter of the lens 924b and the lens 926b are negative and positive, respectively, and the lens 924b and the lens 926b constitute a double cemented lens. In addition to this, the second lens group 920 further includes a lens 928b. The lens 928b is disposed between the lens 926b and the lens 922b, and the diopter of the lens 928b is positive. From this, it is understood that the diopter of the lens 924b, the lens 926b, the lens 928b, and the lens 922b are negative, positive, positive, and positive, respectively.

Specifically, in the present embodiment, the lens 914b is a convex-concave lens having a convex surface toward the magnification side. The lens 916b is a double concave lens, the lens 918b is a lenticular lens, and the lens 919b is a lenticular lens. The lens 924b is a double concave lens, the lens 926b is a lenticular lens, and the lens 928b is a double convex lens. lens. In addition, in the present embodiment, the lens 912b and the lens 922b constituting the fixed focus lens 900b are aspherical lenses, and the remaining seven lenses are spherical lenses. The lens 912b and the lens 922b can effectively improve distortion and astigmatism. Positive and negative combinations in the lens reduce coma and distortion. The double cemented lens formed by the lens 924b and the lens 926b in the second lens group 920b can reduce spherical aberration and chromatic aberration, and the use of the low dispersion material to form the lens 926b or 924b can effectively reduce the chromatic aberration that the large aperture lens is difficult to eliminate. The double cemented lens formed by the lens 916b and the lens 918b in the first lens group 910b can effectively reduce field curvature and chromatic aberration. Making the lens 914b or 922b using a low dispersion material can reduce chromatic aberration. The first lens group 910b and the second lens group 920b each include a set of double cemented lenses to reduce spherical aberration, coma and curvature of field.

An embodiment of the fixed focus lens 900b will be described below. It should be noted that the data listed in Table 21 below is not intended to limit the present invention, and any one of ordinary skill in the art may refer to the present invention after appropriate parameters or settings thereof. It is a change, but it should still fall within the scope of the present invention.

In Table 21, the radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the linear distance between two adjacent surfaces on the optical axis O. For example, the distance between the surfaces S1, that is, the linear distance between the surface S1 and the surface S2 on the optical axis O. For the thickness, refractive index, and Abbe number of each lens and each optical element in the remark column, refer to the values corresponding to the pitch, thickness, and Abbe number in the same column.

Further, in Table 21, the surface S1 is the surface of the lens 914b facing the magnification side, and the surface S2 is the surface of the lens 914b facing the reduction side. The surfaces S3, S4 are the two surfaces of the lens 912b. The surface S5 is the surface facing the magnification side of the lens 916b, the surface S6 is the connection surface of the lens 916b and the lens 918b, and the surface S7 lens 918b faces the surface on the reduction side. The surfaces S8, S9 are the two surfaces of the lens 919b. The surface S10 is the surface facing the magnification side of the lens 924b, the surface S11 is the connection surface of the lens 924b and the lens 926b, and the surface S12 is the surface of the lens 926b facing the reduction side. The surfaces S13, S14 are the two surfaces of the lens 928b, the surfaces S15, S16 are the two surfaces of the lens 922b, and the surfaces S17, S18 are the two surfaces of the optical element 160.

Furthermore, the above-mentioned surfaces S3, S4, S15, and S16 are aspherical, and they can be expressed by the following formula:

In the formula, Z is the offset of the optical axis direction, and c is the reciprocal of the radius of the close spherical surface, that is, the reciprocal of the radius of curvature near the optical axis O (such as the radius of curvature of S1 and S2 in the table). K is the quadric coefficient, y is the vertical height from the optical axis O on the aspherical surface, that is, the height from the center of the lens toward the edge of the lens, and A ₁ ~ A _{7 are} aspherical coefficients, where the coefficients A ₁ and A ₇ are 0. . Listed in Table 2 are the parameter values of the surfaces S3, S4, S15, and S16.

In the present embodiment, the effective focal length of the fixed focus lens 900b is, for example, 14 millimeters (mm), the f-number is f, and the field of view (2 ω) is, for example, 58.4 degrees.

22A to 22C are diagrams of imaging optical simulation data of the fixed focus lens 900b of Fig. 21. Referring to FIG. 22A to FIG. 22C, in FIG. 22A, the pattern of curvature of field and distortion is sequentially from left to right, FIG. 22B is a spherical aberration diagram, and FIG. 22C is a lateral chromatic aberration diagram. As shown in the graphs shown in Figs. 22A to 22C, the fixed focus lens 900b of the present embodiment has good image quality.

Table 23 is the relevant data of the fixed focus lens of the first embodiment to the eleventh embodiment, and the data listed in Table 23 below is not intended to limit the present invention, and any one of ordinary skill in the art is known. After reference to the present invention, appropriate changes may be made to its parameters or settings, but still fall within the scope of the present invention.

In summary, embodiments of the invention include at least one of the following advantages or benefits. In the embodiment of the present invention, since the fixed focus lens can use only five lenses, the fixed focus lens of the present invention has the advantage of reducing the number of lenses to simplify the mechanism design as compared with the conventional lens. Furthermore, since the fixed focus lens of the embodiment of the present invention uses two aspherical lenses, the aberration of the fixed focus lens can be effectively corrected, and other lenses can be spherical lenses, so that the manufacturing cost is effective. Reduced ground. In addition, the f-number ≦2 of the fixed-focus lens of the present embodiment has a large aperture characteristic to improve light use efficiency. It can be seen that the fixed focus lens provided by the embodiments of the present invention has lower cost, smaller volume and better optical characteristics.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention cannot be limited thereto, that is, the patent application according to the present invention The scope of the invention and the equivalent equivalents and modifications of the invention are still within the scope of the invention. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

100, 200, 300, 400, 500, 600, 700, 800, 900, 900a, 900b‧‧‧ fixed focus lens

110, 210, 310, 410, 510, 610, 710, 810, 910, 910a, 910b‧‧‧ first lens group

112, 114, 122, 124, 126, 212, 214, 222, 224, 226, 228, 312, 314, 316, 322, 324, 326, 328, 412, 414, 416, 422, 424, 426, 428, 512, 514, 516, 618, 522, 524, 526, 528, 612, 614, 622, 624, 626, 628, 629, 712, 714, 716, 718, 722, 724, 726, 728, 812, 814, 816, 822, 824, 826, 828, 829, 912, 914, 916, 918, 922, 924, 926, 928, 929, 912a, 914a, 916a, 918a, 922a, 924a, 926a, 928a, 914b, 912b, 916b, 918b, 919b, 922b, 924b, 926b, 928b‧‧‧ lens

120, 220, 320, 420, 520, 620, 720, 820, 920, 920a, 920b‧‧‧ second lens group

130‧‧‧ aperture diaphragm

140‧‧‧Image Processing Components

150‧‧‧glass cover

160‧‧‧Optical components

O‧‧‧ optical axis

S1~S18‧‧‧ surface

1 is a schematic structural view of a fixed focus lens according to a first embodiment of the present invention.

2A to 2C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 1.

3 is a schematic structural view of a fixed focus lens according to a second embodiment of the present invention.

4A to 4C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 3.

FIG. 5 is a schematic structural view of a fixed focus lens according to a third embodiment of the present invention.

6A to 6C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 5.

Fig. 7 is a schematic structural view of a fixed focus lens according to a fourth embodiment of the present invention.

8A to 8C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 7.

Figure 9 is a schematic view showing the structure of a fixed focus lens according to a fifth embodiment of the present invention; Figure.

10A to 10C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 9.

Figure 11 is a schematic view showing the structure of a fixed focus lens according to a sixth embodiment of the present invention.

12A to 12C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 11.

Figure 13 is a schematic view showing the structure of a fixed focus lens according to a seventh embodiment of the present invention.

14A to 14C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 13.

Figure 15 is a schematic view showing the structure of a fixed focus lens according to an eighth embodiment of the present invention.

16A to 16C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 15.

Figure 17 is a schematic view showing the structure of a fixed focus lens according to a ninth embodiment of the present invention.

18A to 18C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 17.

Figure 19 is a schematic view showing the structure of a fixed focus lens according to a tenth embodiment of the present invention.

20A to 20C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 19.

Figure 21 is a structural view showing a fixed focus lens of an eleventh embodiment of the present invention; intention.

22A to 22C are diagrams of imaging optical simulation data of the fixed focus lens of Fig. 21.

100‧‧‧ fixed focus lens

110‧‧‧First lens group

112, 114, 122, 124, 126‧‧ lens

120‧‧‧second lens group

130‧‧‧ aperture diaphragm

140‧‧‧Image Processing Components

150‧‧‧glass cover

160‧‧‧Optical components

O‧‧‧ optical axis

S1~S12‧‧‧ surface

Claims (20)

A fixed focus lens is disposed between an enlarged side and a reduced side, the fixed focus lens includes: a first lens group including a first lens, wherein the first lens is an aspheric lens; and a second a lens group having a positive refractive power disposed between the first lens group and the reduced side, the second lens group including a second lens, and the second lens being an aspheric lens, wherein the fixed lens is f a number ≦2, and the fixed focus lens is focused by moving the first lens group and the second lens group, and the fixed focus lens satisfies 0.1<| f/f1 |<1, 0.2<| f/f2 | 1.5, and 1.5 < L / BFL < 3.5, where f is the focal length of the fixed focus lens, f1 is the effective focal length of the first lens group, f2 is the effective focal length of the second lens group, and L is the total length of the fixed focus lens The BFL is the back focus length of the fixed focus lens. The fixed focus lens of claim 1, wherein the first lens group further comprises a third lens disposed between the first lens and the second lens group or the amplification side and the first lens between. The fixed focus lens of claim 2, wherein the fixed focus lens satisfies 0.1<| fasp1/f1 |<11, wherein fasp1 is an effective focal length of the first lens. The fixed focus lens of claim 1, wherein the first lens is a meniscus lens having a convex surface facing the magnification side, and the diopter of the first lens is negative. The fixed focus lens of claim 1, wherein the The first lens group further includes a third lens and a fourth lens arranged in sequence from the enlarged side to the reduced side, wherein the third lens and the fourth lens are disposed in the first lens and the second lens group And the third lens and the fourth lens form a double cemented lens. The fixed focus lens of claim 5, wherein the diopter of the third lens is negative, and the diopter of the fourth lens is positive. The fixed focus lens of claim 1, wherein the second lens group further comprises a fifth lens and a sixth lens arranged in sequence from the enlarged side to the reduced side, and the fifth lens is The sixth lens constitutes a double cemented lens. The fixed focus lens of claim 7, wherein the refracting power of the fifth lens is negative, and the diopter of the sixth lens is positive. The fixed focus lens of claim 1, further comprising an aperture stop disposed between the first lens group and the second lens group. The fixed focus lens of claim 9, wherein the second lens has a negative refracting power, and the second lens is one of the second lens groups closest to the aperture stop, wherein the fixed focus lens Satisfying 0.2<| f/f1 |<1, 0.3<| f/f2 |<1, and 1.5<L/BFL<3.5, where f is the focal length of the fixed-focus lens and f1 is the effective focal length of the first lens group And f2 is the effective focal length of the second lens group, L is the total length of the fixed focus lens, and BFL is the back focus length of the fixed focus lens. The fixed focus lens of claim 10, wherein the first lens is one of the first lens groups closest to the magnification side, and the fixed focus lens satisfies 0.5<| fasp1/f1 |<3, wherein Fasp1 is the first through The effective focal length of the mirror. The fixed focus lens of claim 10, wherein the first lens group comprises at least two lenses. The fixed lens according to claim 10, wherein the second lens group further comprises a fifth lens and a sixth lens arranged in sequence from the enlarged side to the reduced side, the fifth lens and the The sixth lens is disposed between the second lens and the reduced side. The fixed focus lens of claim 13, wherein the refracting power of the fifth lens and the sixth lens are negative and positive, respectively, and constitute a double cemented lens. The fixed lens according to claim 13 , wherein the second lens group further comprises a seventh lens disposed between the sixth lens and the reduced side, and the refracting power of the seventh lens is positive. The fixed focus lens of claim 9, wherein the second lens has a positive refracting power, and the second lens is one of the second lens groups farthest from the aperture stop, wherein the fixed focus lens Satisfying 0.1<| f/f1 |<1, 0.2<| f/f2 |<1.5, and 1.8<L/BFL<3.5, where f is the focal length of the fixed-focus lens and f1 is the effective focal length of the first lens group And f2 is the effective focal length of the second lens group, L is the total length of the fixed focus lens, and BFL is the back focus length of the fixed focus lens. The fixed focus lens of claim 9, wherein the first lens group comprises at least two lenses. The fixed focus lens of claim 9, wherein the second lens group further comprises a fifth lens and a sixth lens disposed in the hole The light barrier is between the second lens and the fifth lens and the sixth lens form a double cemented lens. The fixed focus lens of claim 18, wherein the refracting power of the fifth lens and the sixth lens are negative and positive, respectively. The fixed focus lens of claim 9, wherein the second lens group comprises at least three lenses, and a diopter of the lens closest to the aperture stop of the second lens group is negative, and the remaining lenses are The diopter is positive.